Gradient vs. Isocratic Elution

In any liquid chromatography experiment, the composition of the mobile phase is very important in the total separation scheme. In Chapter 11, we discussed the role of a liquid mobile phase in terms of the solubility of the mixture components in both phases. Rapidly eluting components are highly soluble 

FIGURE 13.6 (a) Illustration of the gradient programmer hardware and (b) an example of a program. 

Solvent strength is a designation of the ability of a solvent (mobile phase) to elute mixture components. The greater the solvent strength, the shorter the retention times. 

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